Three-dimensional films and television have been well-known, in several different forms. Three-dimensional films have been produced wherein two images are simultaneously projected onto a screen, each image having been photographed from a different angle, and each image being accented for either red or green. The viewer in this system wore glasses having one lens of red and the other of green, so that the images on the screen were filtered appropriately by each lens so that effectively the left eye saw only one image and the right eye saw only the other image, producing the three-dimensional effect.
The described system had one problem in that the composite image tended to be somewhat dark when viewed through the colored lenses. Another problem was in achieving the proper color balance in the composite image, which was often difficult.
Another system which has been used more recently employs time division in the displaying of two different images, one for the left eye and one for the right eye. Thus, the left-eye image is presented for a brief period, then the right-eye image is presented for a similar brief period, substantially without overlap of the two images in time.
Glasses for viewing the three-dimensional system just described, for either movies or television, have generally utilized polarization of the two lenses having liquid crystal material, on a time-alternating basis, as a means for causing each eye to see only its intended image. Most systems have used double polarization in each lens, which is sufficient to block out nearly 100% of the light from the opposite-eye image. Approximately 25% of the light from an image is received through the lens in the "ON" state.
The polarized-lens system suffered from a severe loss of brightness to the viewer. The perceived composite three-dimensional image was so dark as to be uncomfortable in viewing. In addition, the repeated strong contrast between total darkness and even 25% brightness caused additional discomfort to the eyes.
Another disadvantage of the system just described is that it required wires leading from the television or film projector to each pair of glasses, for transmitting the control signal for regulating the "ON" and "OFF" condition of each lens.
It is among the objects of the present invention to improve the visibility, comfort and convenience of use in a time-divided, alternate-image three-dimensional viewing system.